ardop: support version 2

[cbs228]

Specifications for ARDOP version 2 were released 15 May 2018. This new version breaks both RF and TNC compatibility with ARDOP version 1. Since then, "beta" implementations of ARDOP 2 have been released for Windows and Linux. Version 1 is still around, and at least some RMS nodes continue to operate it. But it is likely that version 2 is the future. We should update wl2k-go to support the new TNC.

An initial reading of the new TNC specification indicates that the following commands have changed:

• DIRTYDISCONNECT → ABORT
• ARQBW arguments
• CONNECT → ARQCALL
• ARQTIMEOUT
• BUSYLOCK → BUSYBLOCK
• BUSYDET
• ENABLEPINGACK
• FECMODE arguments
• MONITOR
• NEGOTIATEBW
• PING
• OVER removed
• PING
• PURGEBUFFER
• A variety of RADIO commands were added
• RESTOREBUFFER
• SENDCQ
• TUNERANGE

The following responses have changed:

• CANCELPENDING
• CONNECTED arguments
• CQ
• RADIOFREQUENCY → FREQUENCY
• NEWSTATE arguments
• PENDING
• PING
• PINGACK
• PTT new behavior
• REJECTED...

And probably others. The TNC interface is almost completely different. In addition, CRCs are not used on TCP/IP. (If they ever were.)

[martinhpedersen]

Merged to master in d9a01fe8d953734f295e6620180e656bbf190f25.